What if we just combined all of these ideas and rewarded people for everything?

• Top 10 for highest damage, cumulative across all waves.
• Top 10 highest damage for each wave, separately. (3 waves? Then each has its own high score list.)
• Top 5-10 from each tier.

When rewarding prizes, it goes through those high score lists in order. If your pet qualifies for a top prize in more than one list, it's rewarded based on the first list processed and then ignored on subsequent lists so other people have a chance.

I don't know if this would solve anything. I'm too tired to think it through all the way, but I wanted to throw it out there before I forgot. I might come back to this tomorrow or something. :P